Collapsible multi-sized drill bit and method of use

ABSTRACT

The present invention relates to a collapsible drill bit for use in formation drilling and a method of formation drilling. The drill bit includes a main body having a first cutting diameter and includes a front end with a cutting face supporting one or more cutting elements and a rear end configured to operatively connect to a drill string. The drill bit also includes a retractable portion between the front end and the rear end, the retractable portion including at least one cutting face supporting one or more cutting elements, the retractable portion configured to move between an expanded position in which the retractable portion has a second cutting diameter and a collapsed position in which the retractable portion has a diameter less than or equal to the first cutting diameter. Wherein the retractable portion is caused to move into the collapsed position upon an application of a sufficient force.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional application No. 62/470,965 filed Mar. 14, 2017 and entitled COLLASPIBLE MULTI-SIZED DRILL BIT AND METHOD OF USE, which is incorporated herein by reference.

FIELD OF THE INVENTION

The present concept relates to equipment used in resource drilling and more particularly relates to collapsible multi-sized drill bits and their method of use in oil and resource drilling.

BACKGROUND OF THE INVENTION

In resource drilling operations, it is often, the case that one begins drilling at a larger diameter and then once a certain depth has been reached, drilling then continues on at a smaller diameter. In open hole formation drilling for example, one may begin drilling at a larger diameter until a certain depth has been reached. Once that depth has been reached, the entire drill string must then be stripped out of the hole and the drill bit changed to a smaller diameter drill bit. Then the entire drill string must be replaced down the hole and drilling may continue at the lower depth using a smaller diameter drill bit.

A similar situation exists in existing well bores which require clean out operations.

The existing well bore, for example, may have a 9⅞ inch casing followed by a 6⅝ or 7⅝ inch casings or other standard oil field casing sizes which are cemented in place. There are times when re-drilling is necessary to redevelop an abandoned well for example. In these cases, a tool is used to drill out the cement of the larger sized casings and then the entire drill string is tripped out of the hole and the drill bit replaced with a smaller sized bit and then the drill string is replaced down the hole and drilling continues at the smaller diameter.

There is considerable expense and time expended to remove an entire drill string out of the hole, replacing the drill bit and then placing the entire drill string back down the hole to continue drilling. This change out of the drill bits from a larger diameter to a smaller diameter can cost a significant amount of time to drill rig operators and expense to the drilling process.

Therefore there is a need for a drilling process which could potentially eliminate the need for having to remove the entire drill string in order to change drill bits from a larger diameter to a smaller diameter or to continue drilling.

SUMMARY OF THE INVENTION

The present invention is a collapsible drill bit for use in formation drilling that is comprised of a main body having a first diameter and includes a front end with a cutting face and a rear end adapted to be connected to drill string. The drill bit further includes a retractable portion adapted to move between an expanded position in which the retractable portion has a second diameter and a collapsed position in which the retractable portion has a diameter less than or equal to the first diameter. The retractable portion has at least one cutting face and is moveable to a collapsed position by using one of the following selected from among: dropping a ball, dropping a dart, dropping a plug, over pressurizing the system mechanically, hydraulically or pneumatically.

According to an embodiment, the present invention relates to a collapsible drill bit for use in formation drilling comprises:

-   a main body having a first cutting diameter and includes a front end     with a cutting face supporting one or more cutting elements and a     rear end configured to operatively connect to a drill string; -   a retractable portion between the front end and the rear end, the     retractable portion including at least one cutting face supporting     one or more cutting elements, the retractable portion configured to     move between an expanded position in which the retractable portion     has a second cutting diameter and a collapsed position in which the     retractable portion has a diameter less than or equal to the first     cutting diameter; -   wherein the retractable portion is caused to move into the collapsed     position upon an application of a sufficient force.

In an embodiment, the retractable portion is configured such that when the body is rotated in one direction, the rotational force will keep the retractable portion in the expanded position and when the body is rotated in the opposite direction, the rotational force which will urge the retractable portion into the collapsed position.

In an embodiment, the body comprises a channel formed therein; and an actuation member disposed within the channel, the actuation member moveable between a first position and a second position relative to the body to operably move the retractable portion between the expanded position and the collapsed position, respectively, upon the application of the sufficient force.

In an embodiment, the movement from the first position to the second position causes the retractable portion to move into the collapsed position.

In an embodiment, the retractable position is maintained in the expanded position by one of more retainers, and upon the application of the sufficient force, the retainers become released, and the retractable portion is moved from the expanded position into the collapsed position.

In an embodiment, the retainers are shear pins and the movement of the member causes the retainers become released when the shear pins to be sheared off.

In an embodiment, the member comprises threads and is configured to matingly engage corresponding thread on a torque ring, such that upon the application of the sufficient force, the member forces torque transfer to move the retractable portion between the expanded position and the collapsed position.

In an embodiment, the movement is driven by the application of mechanical force from impact of a plugging means selected from among ball, dart and plug on the actuation member.

In an embodiment, the movement is driven by the application of hydraulic or pneumatic force acting on the member.

In an embodiment, the bit further comprising one or more drill arms operatively connected to the body between the retractable portion and the rear end, supporting one or more cutting elements, the drill arms configured to move between a resting position wherein the arms are closed to the body and an activated position wherein the one or more arms extend away from the body, upon an application of another sufficient force.

In an embodiment, the bit further comprises a second actuation member disposed within the channel and operatively connected to the drill arms, wherein upon the application of the sufficient force, the second actuation member moves between a first position and a second position relative to the body to push the drill arms outwards from the body.

In an embodiment, the outer wall of the second actuation member comprises one or more shoulders defining a diameter greater than a diameter on either side of the shoulder, wherein when the shoulder is displaced upon the application of the sufficient force, the shoulder is moved into contact with the one or more drill arms and the one or more drill arms extend away from the body.

In an embodiment, the retraction of the retractable portion and the actuation of the drill arms are independently actuable.

In an embodiment, the force sufficient to cause the retraction of the retractable portion is less than the force sufficient to cause the actuation of the drill arms.

In an embodiment, the drill arms are reamers defining a preselected diameter, in the activated position.

According to an embodiment, the present invention relates to an extendible bit for use in formation drilling, the bit comprising

-   a hollow body defining a first cutting diameter and includes a front     end with a cutting face supporting one or more cutting elements and     a rear end adapted configured to operatively connect to a drill     string; -   one or more drill arms, supporting one or more cutting elements, the     drill arms configured to move between a resting position wherein the     arms are closed to the body and an activated position wherein the     arms extend away from the body, upon an application of a sufficient     force; and -   an actuation member disposed within the body configured to receive     the sufficient force and operatively connected to a portion of the     one or more drill arms, the actuation member comprises one or more     shoulders defining a diameter greater than a diameter on either side     of the shoulder, wherein when the shoulder is displaced upon the     application of the sufficient force, the shoulder is moved into     contact with the portion of the one or more drill arms and the one     or more drill arms extend away from the body.

According to an embodiment, the present invention relates to a method of formation drilling using a multi-sized drill bit configured to operatively connect to a drill string, the bit defining a cutting diameter, a front end with a cutting face, and a rear end configured to connect to the drill string, a retractable cutting blade defining a cutting profile greater than the cutting diameter of the bit and configured to retract into the body and an extendible cutting blade configured to extend out of the body defining another cutting profile when extended from a rest position, the method comprising:

-   drilling a bore using the retractable cutting blade, wherein the     drilled bore has a diameter defined by the cutting profile; -   applying a first force sufficient to retract the retractable cutting     blade, wherein the applying the first force is insufficient for     extending the extendible cutting blade from the rest position, when     a first desired depth is reached; -   applying a second force sufficient to extend the extendible cutting     blade to the another cutting profile from the rest position after     the retractable cutting blade is retracted; and -   withdrawing the drill bit.

In an embodiment, the method further comprising, after the first depth is reached, drilling deeper into the bore, wherein the drilled bore has a diameter substantially equal to the cutting diameter of the bit, and withdrawing the drill bit after a second desired depth is reached, wherein during the withdrawing, the drilled bore having the diameter substantially equal to the cutting diameter of the bit is enlarged by the extended extendible cutting blade to the another cutting profile.

In an embodiment, the method further comprising applying a third force sufficient to retract the extended extendible cutting blade.

In an embodiment, the cutting profile is larger or smaller than the another cutting profile.

In an embodiment, the bit comprises a body having a channel formed therein; a first actuation member disposed within the channel, the first actuation member moveable between a first position and a second position relative to the body to retract the retractable cutting blade into the body upon the application of the first force; and a second actuation member disposed within the channel, wherein upon the application of the second force, the second actuation member moves between a first position and a second position relative to the body to push the extendible cutting blade outwards from the body.

BRIEF DESCRIPTION OF THE DRAWINGS

The present concept will now be described by way of example only with reference to the following drawings in which:

FIG. 1 is a schematic side elevation view of a collapsible drill bit shown in an expanded position;

FIG. 2 is a schematic rear end plan view of a collapsible drill bit shown in an expanded position;

FIG. 3 is a schematic side elevation view of a collapsible drill bit shown in the collapsed position;

FIG. 4 is a schematic front plan view of a collapsible drill bit shown in a collapsed position;

FIG. 5 is a schematic side elevation view of a collapsible drill bit using a mechanical retraction system which is triggered by counter rotation;

FIG. 6 is a schematic side elevation view of a collapsible drill bit mechanism for use with a ball or other plugging device dropped down the centre of the tool;

FIG. 7 is a schematic side elevation view of the collapsible drill bit mechanism shown in FIG. 6 in a collapsed position;

FIG. 8 is a schematic side elevation view of a collapsible drill bit mechanism shown in FIG. 6 in the expanded position;

FIG. 9 is a schematic side elevation view of a collapsible drill bit mechanism using a rack and pinion gear system shown in the expanded position;

FIG. 10 is a schematic side elevation view of a collapsible drill bit mechanism shown in the collapsed position;

FIG. 11 is a schematic side elevation view of a collapsible drill bit mechanism using a set of scissor links shown in the expanded position;

FIG. 12 is a schematic side elevation view of a collapsible drill bit mechanism shown in the retracted position;

FIG. 13 is a schematic front elevation view of a collapsible drill bit mechanism using a forced torque system for hinging open the retractable blades;

FIG. 14 is schematic side elevation view of a collapsible drill bit mechanism using a low pitched spline forced torque retraction system shown in the expanded position;

FIG. 15 is a schematic side elevation view of a collapsible drill bit mechanism using a low pitched spline forced torque retraction system shown in the partially expanded position;

FIG. 16 is a schematic side elevation view of a collapsible drill bit mechanism using a low pitched spline forced torque retraction system shown in the collapsed position;

FIG. 17 is a schematic front elevation view of a collapsible drill bit mechanism using a forced torque system together with a cam drive shown in the expanded position;

FIG. 18 is a schematic front elevation view of a collapsible drill bit mechanism using a forced torque system together with a cam drive shown in the retracted position;

FIG. 19 is a schematic side elevation view of a collapsible drill bit use with a ball or other plugging device dropped down the centre of the tool shown in an expanded position;

FIG. 20 is a schematic side elevation view of a collapsible drill bit for use with a ball or other plugging device dropped down the centre of the tool shown in the collapsed position;

FIG. 21 is a schematic side elevation view of a collapsible drill bit shown in an expanded position and wherein a reamer is shown in a rest position according to another embodiment of the present invention;

FIG. 22 is a longitudinal section through the collapsible drill bit of FIG. 21;

FIG. 23 is a schematic side elevation view of the collapsible drill bit shown in an collapsed position and wherein the reamer is shown in a rest position;

FIG. 24 is a longitudinal section through the collapsible drill bit of FIG. 23;

FIG. 25 is a schematic side elevation view of a collapsible drill bit wherein the reamer is shown in an activated position;

FIG. 26 is a longitudinal section through the collapsible drill bit of FIG. 25; and

FIG. 27 is a schematic side elevation view of an actuation member for moving the reamer between the rest and activated positions shown in isolation from the collapsible drill bit of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will be made below in detail to exemplary embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numerals used throughout the drawings refer to the same or like parts.

The present invention relates to a collapsible drill bit 100 and its method of use. The collapsible drill 100 according to the present invention is shown in the drawings and by way of example only and with reference to a first embodiment which is shown in FIGS. 1 through 4. Collapsible drill bit 100 comprises a main body 102, a primary bit 104, cutting face 103 and cutting blades 105 located at a front end 108, a plurality of retractable blades 106 located on cutting face 111, female connection 114 for connecting to a drill string (not shown) located at a rear end 110, and one or more nozzles 112 for delivering one or more fluids.

As shown in FIG. 1, primary multi-blade bit 104 comprise polycrystalline diamond compact (PDC) cutters. However, primary multi-blade bit 104 could also be a roller cone, diamond impregnated, and/or carbide bit. Primary bit 104 may be rigidly attached to main body 102 or may be replaceable via a connection system to main body 102. While primary bit 104 is depicted as a multi-blade primary bit 104, any known style suitable for the particular formation being drilled could be used as primary bit 104.

Shown in FIG. 1 is the collapsible drill bit 100 in an expanded position 116 and depicting first diameter 107 and second diameter 109 of main body 102. FIG. 2 shows the same collapsible drill bit 100 in the expanded position 116 with retractable blades 106 shown in a rear end plan view.

In FIG. 3, the same collapsible drill bit 100 is depicted in schematic fashion in a collapsed position 118 wherein the retractable blades 106 are retracted within the main body 102 of collapsible drill bit 100.

FIG. 4 shows schematically, collapsible drill bit 100 in the collapsed position 118 in a front plan view of the collapsible drill bit 100.

FIG. 5 through to FIG. 18 depict further collapsible drill bit mechanisms which are used in order to retract retractable blades 106 from an expanded position 116 to a retract collapsed position 118. These will be described more fully below.

In one embodiment, in the expanded position 116, the collapsible drill bit 100 may, for example, have an 8.5 inch outside diameter 109 and in the collapsed position 118, can collapse down into a 6 inch outside diameter 107.

There are numerous advantages of a collapsible drill bit 100. In many operations, certain procedures require the use of two or more tools specialized for each specific size to be drilled out. In one embodiment, collapsible drill bit 100 can do the job of two or more specialized tools. For example, in some operations, the entire drill string must be tipped out of the hole and a tool change must be undertaken in order to continue on drilling. The use of a collapsible drill bit 100 obviates the requirement for two specialized tools and prevents the need to strip out of the hole in order to change out the drill bits.

Additionally, the collapsible drill bit 100 for example, can be used to drill open hole formations at a larger diameter when retractable blades 106 are in the expanded position 116 and then to collapse to a smaller diameter such as when retractable blades 106 are in the collapsed position 118 and continue drilling.

In other examples uses, the collapsible drill bit 100 can also be used to drill out cement in existing well bores in clean out operations. An existing well bore may have a 9⅞ inch casing following by a 6⅝ inch or 7⅝ inch casing or other standard oil field casing which are cemented in place. To ensure drift of production tooling and/or for re-drilling to redevelop the abandoned well, a tool is used to drill out the cement of the larger sized casing when collapsible drill bit 100 is in the expanded position 116 and then the collapsible drill bit 100 is collapsed down to a smaller diameter when it is in the collapsed position 118 to continue drilling with a smaller diameter drill bit. The collapsible drill bit 100 would eliminates the need to strip out the drill string to change to a smaller diameter bit.

Female connection 114 is shown as a box connection, but could be a male connection or a hex or bolt on connection.

Nozzles 112 can be either fixed or replaceable jet nozzles for optimizing hydraulics. Nozzles 112 may also comprise outer jet nozzles (not shown) configured to self-plug when the retractable blades 106 are moved into the collapsed positon 118.

As shown in the figures, collapsible drill bit 100 is shown to having four blades 106, however the bit 100, is not limited to four blades and can have any number of blades suitable for the application.

Collapsible drill bit 100 for example is set in the larger diameter position, namely in expanded position 116 and is collapsed into the collapsed position 118 by mechanical, hydraulic or pneumatic pressure.

Methods of Retraction

The first method for retraction is a mechanical counter rotation system which is depicted schematically as collapsible drill bit 200.

Collapsible drill bit 200 includes a drill body 202, retractable blades 206, and is shown in the expanded position 216.

The normal drilling direction (clockwise) is shown as 208 in which case drilling force 212 is applied to retractable blades 206.

In order to retract retractable blades 206, one reverses the rotation (counter clockwise) of collapsible drill bit 200 by applying a retracting force 214 against the retractable blades 206 which is done by counter rotation retraction direction 210.

FIG. 6 shows a collapsible drill bit mechanism 300 which comprises an actuation member 301 which includes a shift sleeve 322 having a ball receptacle 330, and a shaft 320 carrying the shift sleeve 322. Retractable blades 306 held in place and connected to the body by chain link connection 324 and is shown in the expanded position 316. Drill bit body 102 can comprise a channel (not shown) configured to receive the actuation member 301 and permit movement of the actuation member 301 therein. In FIG. 7, collapsible drill bit 300 is shown in the collapsed position 318, together with ball receptacle 330 showing the ball force direction 334 and the retraction direction 332.

FIG. 8 shows collapsible drill bit mechanism 300 in the expanded position.

With this particular mechanism, shift sleeve 322 moves down to retract blades 306 upon impact with a ball (not shown) or any other plugging means that are dropped down and into the channel of the tool. Plugging means dropped down in the channel will exert a certain force upon the actuation member when impacted thereon.

There may be, for example, a shear pin housing 340 containing shear pins. When the drill bit mechanism is over-pressured (or otherwise subjected to a sufficient force), the pins would shear and the tool would shift downwardly with shift sleeve 322. This would place the tool in the collapsed position 318. It is also possible to retract the blades using hydraulic or pneumatic over-pressure rather than use of a ball. Rather than using chain link connection 324, it is possible to use a steel cable or steel rope as an alternative to the chain link connection not shown in the diagrams.

FIGS. 9 and 10 show a collapsible drill bit mechanism 400 which includes a gear rack 410 and a gear pinion 412 and is shown in the expanded position 416 wherein in retractable blades 406 are extended.

In FIG. 10, collapsible drill bit mechanism 400 is shown in the collapsed position 418 wherein the gear pinion rotates about pinion shaft 420. Again by over-pressuring the system, either pneumatically, hydraulically or by placing a ball down the centre of the hole, sheer pins would be sheered thereby moving retractable blades 406 from the expanded position 416 to the collapsed position 418.

FIGS. 11 and 12 show a collapsible drill bit mechanism 500 which uses a set of scissor links namely outer scissor links 510, inner scissor links 512 and is showing the collapsible drill bit mechanism 500 in expanded position 516 with retractable blade 506 in the completely expanded position. Again by over-pressuring the system using either a ball, pneumatically, or hydraulically over-pressuring one is able to move collapsible drill bit mechanism 500 from the expanded position 516 into the retracted position 518 as shown in FIG. 12.

FIG. 13 shows collapsible drill bit mechanism 600 which uses a forced torque system, namely a low pitched thread 610, a torque ring 612, hinges 614 and retractable blades 606, which are shown in the expanded position 616, a steep multi-start low pitch thread 610 forces torque transfer to retractable blade 606, when the system is over-pressurized using a ball pneumatically or hydraulically. The rotation force moves cutting blades into a closed position with the hinge 614.

Collapsible drill bit mechanism 700 includes a low pitch spline 710, a ball receptacle 712, a ball 714 and is shown in the expanded position 716. Collapsible drill bit mechanism 700 further includes a female set of splines 720 and a rotating plate 722. Retractable blades 716 is shown in the expanded position in FIG. 14, in a partially collapsed position in FIG. 15 and in the collapsed position 718 in FIG. 16. When ball 714 is dropped on to ball receptacle 712, this forces low pitched spline 710 into female spline 720, thereby rotating rotating plates 722, and retracting retractable blades 716 into the collapsed position 718 as shown in FIG. 16.

Collapsible drill bit mechanism 800 is shown in FIGS. 17 and 18 and includes a cam drive 810 and a retractable blade 806 in the expanded position 816. Collapsible drill bit 800 is shown in the collapsed position 818 in FIG. 18. In this particular case, collapsible drill bit mechanism 800 uses a cam located at the bottom of the body, namely cam drive 800 in order to retract retractable blades 806 closer to the body.

Collapsible drill bit 900 is shown in FIGS. 19 and 20 and includes a main body 902 defining a channel 901, a multi-blade primary bit 904 located at a front end 908, a number of retractable blades 906, and female connection 914 located at a rear end 910. In FIG. 19 the collapsible drill bit 900 is shown in an expanded position 916.

In FIG. 20, the same collapsible drill bit 900 is depicted in a collapsed position 918 wherein the retractable blades 106 are retracted within the main body 902 of collapsible drill bit 900. Collapsible drill bit 900 is collapsed by either dropping a ball 915, a dart, a plug or any other plugging devices, into the channel 901, or otherwise over-pressuring the drilling system mechanically, hydraulically or pneumatically.

Extendible Reamer

FIGS. 21 to 27 show another embodiment of the collapsible drill bit according to the present invention. FIGS. 21 and 22 show a collapsible bit 1000 comprising a main body 102 defining a channel 1101, a primary bit 104, cutting face 103 and cutting blades 105 located at a front end 108, a plurality of retractable blades 106 located on cutting face 111, female connection 114 for connecting to a drill string (not shown) located at a rear end 110, and one or more nozzles (not shown).

As shown in FIGS. 21 to 22, the collapsible drill bit 1000 is in an expanded position 116 wherein a plurality of retractable blades 106 defining first diameter 107 and main body 102 having second diameter 109.

As shown in FIGS. 23 and 24, upon the application of a sufficient force, drill bit 1000 can be caused to retract retractable blades 106. Drill bit 1000 can include, but is not limited to, mechanisms 300, 400, 500, 600, 700, and 800 discussed above for retracting retractable blades 106. For example, as shown in FIGS. 23 and 24, the retraction of retractable blades 106 is accomplished by dropping a ball 915 with a first dimension down the channel 1101, wherein the downward movement of the dropped ball 915 exerts a force sufficient to cause the retraction of retractable blades 106.

As shown in FIGS. 21 to 26, drill bit 1000 further comprises one or more drill arms also referred to as reamers 1130 between the retractable blades 106 and the rear end 110. As will be described below, reamers 1130 are configured to move from a rest position where reamers are closed against body 102 and have an external profile that does not substantially contact the surface of the bore and an activated position wherein reamers 1130 are expanded away from the body 102 and have an external profile that substantially contacts the surface of the bore to ream the casing bore. Once activated, reamers 1130 can also be configured to move back into the rest position from the activated position. In other words, reamers can be reversibly extendible reamers.

As shown in FIGS. 21 to 26, and more particularly in FIG. 27, reamers 1130 comprise a first end 1132 fitted with a plurality of cutting elements 1134 made of a hard material, such a PDC, and a second end 1136 opposite the first end 1132. Reamers are configured to move within a scrapper seat 1140 formed from the wall of body 102, wherein the inward movement of reamers is limited by an interior wall 1142 of the body and the outward movement is limited by a locking plate 1144. The second end 1136, opposite the first end 1132, is operatively engaged to an actuation member 1301.

Actuation member 1301 comprises a hollow sleeve 1322 defining a lumen 1340 having an internal diameter and a ball receptacle 1330 at one end configured to receive one or more balls 915 of suitable dimensions. As will be appreciated, sleeve 1322 is configured to allow those balls having a diameter about less than the internal diameter 1340 of the sleeve 1322 to pass therethrough. Those balls having a diameter about equal to or are larger than the internal diameter 1340 of the sleeve 1322 will not be able to pass into the lumen 1340 and will rest on the ball receptacle 1330.

The outer wall 1350 of sleeve 1322 is configured to operatively engage the second end of the reamers 1130, to move reamers 1130 from the rest positon, to the activated position, and back to the rest position, when sleeve 1322 is acted upon by a sufficient force. Sleeve 1322 comprises one or more tapered shoulders 1352, wherein the outside diameter of the sleeve 1322 at the tapered shoulder 1352 is greater than the outside diameter of the sleeve 1322 on either side 1353 of the tapered shoulder 1352.

As shown in FIGS. 23 and 24, in the rest position, the second end of the reamers 1130 engage upon a portion of the outer wall of sleeve 1322 between the tapered shoulder 1352 and therefore, reamers 1130 remain closed against the body.

As shown in FIGS. 25 and 26, upon receiving a sufficient force, such as from the impact from ball 1115, the actuation member 1301 is moved downwards from a first position to a second position. The downward shift moves the second end 1136 of reamers 1130 onto the shoulder 1352 to cause the reamers 1130 to be pushed outwards and expand away from the body 102 a distance about equal to the height of the tapered shoulder 1352 to assume the activated position.

The mechanism to move the reamers into the activated position from the rest position can the mechanism similarly used to first move the retractable blades 106 into the collapsed position 118 from the initial expanded position 116. As shown, in FIGS. 21 to 26, collapsible drill bit 1000 may include both actuation member 301 and actuation member 1301. A first ball 915 having a dimension which is smaller than the lumen of the actuation member 1301 is dropped into the channel 1101. This first ball 915 passes through the actuation member 1301 on its way down to impact the actuation member 301 with a sufficient force to retract retractable blades 106. When it is desired, a second ball 1115 having a dimension that is greater than the first ball 915 is dropped into the channel 1101 and this second ball 1115 impacts actuation member 1301 with a sufficient force to expand the reamers 1130 away from the body. Therefore, the collapsible drill bit 1000, is configurable such that a user can perform sequential independent actions by selectively retracting blades 106 and once the blades 106 are retracted, then selectively extending reamers 1130.

In other embodiments, the sufficient force to move the reamers 1130 into the activated position is greater than the force used to move the retractable blades 106 into the collapsed position 118 from the initial expanded position 116.

With reference to FIGS. 25 to 27, once in the activated position, reamers 1130 can also be configured to move back into the rest position. Channel 1101 may be configured to have a length that provides for an additional gap 1354 which permits the actuation member 1301 to be further displaced downward upon receipt of another force. Although not shown, another force, in the example form of yet another ball would force actuation member 1301 into the gap 1354 and consequently, reamer 1130 would be displaced from shoulder 1352, and engage and engage and rest on a portion of the wall to one side of the shoulder 1352 and revert back into the rest position wherein the reamers 1130 are closed to the body 102.

While the force used to move reamers 1130 from the rest position to the activated position and vice versa has been shown to a mechanical force from the impact of the ball, the ball can be replaced with any plugging means, as discussed above, adapted to displace actuation member 1301. Moreover, it will be appreciated that the force is not so limited to mechanical forces and can be hydraulic or pneumatic forces or any combination thereof. For example, instead of using a plugging means, the collapsible drill bit 1110 can be connected to a hydraulic system and the over-pressuring with differential pressure through the use of a pump (not shown) to provide a first pressure sufficient to close the retractable blades 106, and then the system charged at a second pressure greater than the first pressure, which causes the reamers 1130 to become activated and extend away from the body 102.

According to an embodiment, the collapsible drill bit according the present invention is operated as herein described.

The collapsible drill bit according the present invention can combine 3 stages of drilling without the need for post drilling interventions. The bit 1000 can provide for at least 3 distinct hole/well bore sizes and can be useful for at least three types of drilling situations. Furthermore, the user can selectively and independently change hole/well bore sizes depending on the stage of drilling and as desired.

Example 1 (well clean out application). Drill inside of larger diameter casing. Arrive at liner hanger. Collapse retractable blades 106 by dropping a first ball 915 having a first diameter into the channel 1101. Continue drilling using the primary bit 104 through production casing wherein the size of the bore is substantially equal to the diameter of the primary bit 104. At the desired depth, the scraper blades 1130 are activated by dropping a second ball 1115 having a second diameter greater than the first diameter of the first ball 915 into the channel 1101. Simultaneously retrieve bit and scrape production casing hole to desired reaming size using the scraper blades 1130.

Example 2 (maintain hole gauges size despite continuous bit wear): Drill large diameter hole for surface casing, collapse retractable blade 106 and continue to drill production casing hole size using the primary bit 104. Activate reamers 1130 to maintain hole gauge at desired depth. This is particularly useful in situations when the primary bit wear results in a smaller than derived diameter hole. The reamer is able to compensate for the undersize primary bit.

Example 3 (multi size intervention): Drill key well sections at various desired sizes in a single run without tripping. This can be accomplished with different combinations of retractable blades 106, primary bit 104, and reamers 1130 of varying diameters.

The embodiments of the present application described above are intended to be examples only. Those of skill in the art may effect alterations, modifications and variations to the particular embodiments without departing from the intended scope of the present application. In particular, features from one or more of the above-described embodiments may be selected to create alternate embodiments comprised of a subcombination of features which may not be explicitly described above. In addition, features from one or more of the above-described embodiments may be selected and combined to create alternate embodiments comprised of a combination of features which may not be explicitly described above. Features suitable for such combinations and subcombinations would be readily apparent to persons skilled in the art upon review of the present application as a whole. Any dimensions provided in the drawings are provided for illustrative purposes only and are not intended to be limiting on the scope of the invention. The subject matter described herein and in the recited claims intends to cover and embrace all suitable changes in technology. 

1. A collapsible drill bit for use in formation drilling comprises: a main body having a first cutting diameter and includes a front end with a cutting face supporting one or more cutting elements and a rear end configured to operatively connect to a drill string; a retractable portion between the front end and the rear end, the retractable portion including at least one cutting face supporting one or more cutting elements, the retractable portion configured to move between an expanded position in which the retractable portion has a second cutting diameter and a collapsed position in which the retractable portion has a diameter less than or equal to the first cutting diameter; wherein the retractable portion is caused to move into the collapsed position upon an application of a sufficient force.
 2. The bit of claim 1 wherein the retractable portion is configured such that when the body is rotated in one direction, the rotational force will keep the retractable portion in the expanded position and when the body is rotated in the opposite direction, the rotational force which will urge the retractable portion into the collapsed position.
 3. The bit of claim 1 wherein the body comprises a channel formed therein; and an actuation member disposed within the channel, the actuation member moveable between a first position and a second position relative to the body to operably move the retractable portion between the expanded position and the collapsed position, respectively, upon the application of the sufficient force.
 4. The bit of claim 3 wherein the movement from the first position to the second position causes the retractable portion to move into the collapsed position.
 5. The bit of claim 4 wherein the retractable position is maintained in the expanded position by one of more retainers, and upon the application of the sufficient force, the retainers become released, and the retractable portion is moved from the expanded position into the collapsed position.
 6. The bit of claim 5 wherein the retainers are shear pins and the movement of the member causes the retainers become released when the shear pins to be sheared off
 7. The bit of claim 4 wherein the member comprises threads and is configured to matingly engage corresponding thread on a torque ring, such that upon the application of the sufficient force, the member forces torque transfer to move the retractable portion between the expanded position and the collapsed position.
 8. The bit of claim 3 wherein the movement is driven by the application of mechanical force from impact of a plugging means selected from among ball, dart and plug on the actuation member.
 9. The bit of claim 3 wherein the movement is driven by the application of hydraulic or pneumatic force acting on the member.
 10. The bit of claim 1 further comprising one or more drill arms operatively connected to the body between the retractable portion and the rear end, supporting one or more cutting elements, the drill arms configured to move between a resting position wherein the arms are closed to the body and an activated position wherein the one or more arms extend away from the body, upon an application of another sufficient force.
 11. The bit of claim 10 further comprises a second actuation member disposed within the channel and operatively connected to the drill arms, wherein upon the application of the sufficient force, the second actuation member moves between a first position and a second position relative to the body to push the drill arms outwards from the body.
 12. The bit of claim 11 wherein the outer wall of the second actuation member comprises one or more shoulders defining a diameter greater than a diameter on either side of the shoulder, wherein when the shoulder is displaced upon the application of the sufficient force, the shoulder is moved into contact with the one or more drill arms and the one or more drill arms extend away from the body.
 13. The bit of claim 10 wherein the retraction of the retractable portion and the actuation of the drill arms are independently actuable.
 14. The bit of claim 10 wherein the force sufficient to cause the retraction of the retractable portion is less than the force sufficient to cause the actuation of the drill arms.
 15. The bit of claim 10 wherein the drill arms are reamers defining a preselected diameter, in the activated position.
 16. An extendible bit for use in formation drilling, the bit comprising a hollow body defining a first cutting diameter and includes a front end with a cutting face supporting one or more cutting elements and a rear end adapted configured to operatively connect to a drill string; one or more drill arms, supporting one or more cutting elements, the drill arms configured to move between a resting position wherein the arms are closed to the body and an activated position wherein the arms extend away from the body, upon an application of a sufficient force; and an actuation member disposed within the body configured to receive the sufficient force and operatively connected to a portion of the one or more drill arms, the actuation member comprises one or more shoulders defining a diameter greater than a diameter on either side of the shoulder, wherein when the shoulder is displaced upon the application of the sufficient force, the shoulder is moved into contact with the portion of the one or more drill arms and the one or more drill arms extend away from the body.
 17. A method of formation drilling using a multi-sized drill bit configured to operatively connect to a drill string, the bit defining a cutting diameter, a front end with a cutting face, and a rear end configured to connect to the drill string, a retractable cutting blade defining a cutting profile greater than the cutting diameter of the bit and configured to retract into the body and an extendible cutting blade configured to extend out of the body defining another cutting profile when extended from a rest position, the method comprising: drilling a bore using the retractable cutting blade, wherein the drilled bore has a diameter defined by the cutting profile; applying a first force sufficient to retract the retractable cutting blade, wherein the applying the first force is insufficient for extending the extendible cutting blade from the rest position, when a first desired depth is reached; applying a second force sufficient to extend the extendible cutting blade to the another cutting profile from the rest position after the retractable cutting blade is retracted; and withdrawing the drill bit.
 18. The method of claim 17 further comprising, after the first depth is reached, drilling deeper into the bore, wherein the drilled bore has a diameter substantially equal to the cutting diameter of the bit, and withdrawing the drill bit after a second desired depth is reached, wherein during the withdrawing, the drilled bore having the diameter substantially equal to the cutting diameter of the bit is enlarged by the extended extendible cutting blade to the another cutting profile.
 19. The method of claim 17 further comprising applying a third force sufficient to retract the extended extendible cutting blade.
 20. The method of claim 17 wherein the cutting profile is larger or smaller than the another cutting profile.
 21. The method of claim 17 wherein the bit comprises a body having a channel formed therein; a first actuation member disposed within the channel, the first actuation member moveable between a first position and a second position relative to the body to retract the retractable cutting blade into the body upon the application of the first force; and a second actuation member disposed within the channel, wherein upon the application of the second force, the second actuation member moves between a first position and a second position relative to the body to push the extendible cutting blade outwards from the body. 